langtools/src/jdk.compiler/share/classes/com/sun/tools/javatest/main/Option.java has a debug print statement that has accidentally been left in.

$ hg diff -R langtools
diff -r 2cf9f4818c9a src/jdk.compiler/share/classes/com/sun/tools/javac/main/Option.java
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/main/Option.java Wed Nov 23 19:15:26 2016 +0000
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/main/Option.java Wed Nov 23 19:25:18 2016 -0800
@@ -682,7 +682,6 @@
                 Class.forName(JDK9Wrappers.VMHelper.VM_CLASSNAME);
                 String[] runtimeArgs = JDK9Wrappers.VMHelper.getRuntimeArguments();
                 for (String arg : runtimeArgs) {
- System.err.println("runtime arg: " + arg);
                     // Handle any supported runtime options; ignore all others.
                     // The runtime arguments always use the single token form, e.g. "--name=value".
                     for (Option o : getSupportedRuntimeOptions()) {